Tag: Colt

There have been attempts to fire grenades from the infantryman’s weapon since the 17th century. Up until the 1960s these almost entirely involved muzzle attachments or grenades which could be fired off the end of a rifle’s barrel. In May 1963, the US military called for a new ‘underslung’ grenade launcher to complement the AR-15/M16, then in early testing. The grenade launcher program had its roots in the ultimately unsuccessful Special Purpose Individual Weapon (SPIW) program which had begun in 1952.

While a series of designs were developed by various manufacturers and designers, May 1964 saw Colt unveil the CGL-4. The Colt was tested against designs from Springfield Armory and Ford, a design from AAI was promising but it was not able to chamber the 40x46mm rounds used by the M79 and was rejected. The US military sought munitions commonality between the M79, already in service, and the new rifle-mounted grenade launcher.

Left side view of the XM148’s bulky tangent sight (Vic Tuff)

In March 1965, the CGL-4 was chosen for further testing and a contract for 30 launchers was signed. The CGL-4 was reportedly developed by Karl Lewis and Robert E. Roy in just 48 days. However, the design was complex. To load the barrel housing slid forward allowing a grenade to be placed in the breech, the weapon was then cocked and a long trigger, which projected back towards the rifle’s trigger guard, could be pulled to fire the weapon.

Despite some problems with barrel housings cracking an order for 10,500 of the new launchers, now designated the XM148, was placed in January 1966. Production capacity issues and problems with the launcher’s sight lead to production delays and it wasn’t until December 1966, that the first shipment of 1,764 launchers arrived in Vietnam for field testing.

Right side view of the XM148’s trigger, cocking mechanism and pistol grip (Vic Tuff)

Initial reports from the field were promising with troops praising the “tactical advantage of both the point fire and area fire system” concept. The XM148 was well received by the SEALs and the Australian SAS. The armourers of the Australian SAS, deployed to Vietnam with the 1st Australian Task Force, were also hard at work attaching XM148s to L1A1 rifles. Removing the L1A1′s handguard and attaching the XM148 to the rifle’s barrel.

Field testing was carried out by 12 units from six different divisions which were operating in various parts of Vietnam. This gave a wide variety of terrains and yielded some interesting results. In general it was found that the XM148 decreased rate and quantity of the grenadier’s fire, it slowed his reaction times when firing at a target, it hampered his movement in dense vegetation and also meant the grenadier had to spend longer caring for his weapon.

XM148 with breech open (Vic Tuff)

It was noted that the sight mount which was overly complex and prone to snagging on brush and kit, it was also felt that too much force was needed to cock the XM148 (around 30 lbs) and the trigger mechanism was felt to be overly complex and difficult to repair and disassemble. One safety concern was the XM148′s long trigger bar, which could snag and launch a round – not ideal for special forces patrols infiltrating through thick bush. Problems with the launcher’s quadrant sights also continued causing deflection errors out at longer ranges. The bulkiness of the sights exasperated these problems as when they were knocked the XM148′s zero could be effected. The XM148 also precluded the use of a bayonet as when fired it would blow the bayonet off the muzzle. Overall, troops felt the XM148 was too fragile and complex for use in the field.

At least one unit found use for the launchers, the 1st Cavalry Division (Airmobile)’s Operational Report for Quarterly Period Ending 31 October 1967, noted that the XM148

“proved unsatisfactory in infantry units due to its lack of durability; consequently, USARV directed that they be turned in. However, 1/9 Cav has devised a method of mounting the launcher coaxially on the M60C machine gun used by scout observers on OH-13 scout helicopters. Durability in this environment is
not a problem since the weapon deos not receive the rough handling it did in the hands of ground troops. Firepower on scout helicopters is significantly increased. Fifty-two XM148s have been retained for use by 1/9 CAV.”

Finally, despite Colt’s efforts to rectify the growing list of problems the Army Concept Team In Vietnam deemed the XM148 unsatisfactory for deployment in Vietnam and recommended they be removed from service and a new improved launcher be developed. This was a massive blow to Colt who had already manufactured 27,400 XM148s. Many of these were already in Vietnam.

The US Army launched the Grenade Launcher Attachment Development (GLAD) program in the summer of 1967. A large number of manufacturers submitted designs including Colt, who offered the improved Henry Into-designed CGL-5. The Army turned down Colt’s offer of 20 free improved launchers and rejected the CGL-5 outright. The GLAD program saw the resurgence of the earlier AAI design, designated the XM203, this simple design, now chambering the 40x46mm shell, was eventually selected in August 1968. Ironically, as AAI was predominantly a research and development company and after an initial run of 10,000 made by AAI, Colt was subsequently awarded the contract to manufacture the M203 from 1971 onwards.

While the XM148 proved to be a failure it played an important role in proving the operational viability of the rifle mounted grenade launcher system. The muzzle-launched rifle grenade is all but obsolete, superseded by the under-slung grenade launcher.

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My thanks to the Cody Firearms Museum, at the Buffalo Bill Centre of the West, for allowing me to film the revolver. I am very lucky to have handled it as it is normally on display.

The US Patent Office granted Samuel Colt a patent for his ‘Revolving Gun’ in February 1836 (US #9430X). Colt had already patented his design in Britain in October 1835 – at the age of just 21. He subsequently patented his design across Europe and worked with Baltimore gunsmith John Pearson to build a number of prototype revolvers. Colt’s pistol was not the first revolver but it did embody a number of important features combining the use of percussion caps and a bored-out cylinder with a single action trigger mechanism and cylinder locking bar.

With backing from his cousin and other investors Colt established the Patent Arms Company, building afactory in Paterson, New Jersey in late 1836. The Patent Arms Company produced a variety of revolvers in different sizes including pocket, belt and holster models. The .28 calibre Pocket Model No.1 being the smallest and the .36 calibre No.5 holster revolver being the largest. The company produced approximately 2,300 – 2,800 firearms (sources have various estimates on just how many revolvers and revolving rifles were manufactured) before the company collapsed, due to insufficient sales, in 1842.

The Colt Paterson

It was the No.5 which saw the greatest sales with small numbers being purchased by the Texas Rangers, Texan Navy and private citizens. The US Army reportedly tested Colt’s revolver in February and June 1837, finding a number of weaknesses to the design. Despite the approval of President Andrew Jackson the US military remained largely uninterested in the Paterson.

Small numbers of the revolvers were purchased by the U.S. government including 100 for the Navy in 1841 and 50 for the Army in 1845 after the company had collapsed. The Republic of Texas also purchased 180 revolvers for its navy in 1839.

The Paterson has a number of interesting features and lacks some components that would become standard on Colt’s later revolvers. The Patersons had octagonal barrels and were sold in a number of barrel lengths ranging from 2.5 to 9 inches, with 7.5 and 9 inches being the most popular. The barrel assembly attached to the receiver via the cylinder axis pin which was locked together by a wedge – a method which would be used in Colt pistols for over 30 years. They had a small front sight and a notch cut into the hammer that acted as a rear sight. The pistols had no trigger guard, instead they had a folding trigger, which deployed when the weapon was fully cocked. Initially, the Patersons lacked a loading lever beneath the barrel. Instead the cylinder was removed to enable loading and capping with a separate loading tool. Another characteristic of the belt and holster Patersons was their flared pistol grips.

Despite this Colt’s .36 calibre No.5 revolvers proved popular with Texas Rangers, so much so that workers often referred to it as ‘The Texas Arm’, who were frequently engaged in skirmishes with Mexicans and Native Americans. During one engagement with a large Comanche warriors along the Guadeloupe River one ranger recalled: “They were two hundred in number, and fought well and bravely, but our revolvers as fatal as they were astonishing, put them speedily to flight.”

Despite the Patterson’s relatively small calibre, lack of an integral loading arm and the frailties of the design (such as a bent axis pin) the revolver’s five round cylinder offered the men wielding them five times the firepower of their muzzle-loading, single shot pistols.

Despite the limited success of Colt’s revolver the design still needed improvements and Colt became determined that the path to success was through military contracts. Sadly, for Colt there weren’t forthcoming and the Patent Arms Company collapsed in 1841/2.

It was the Mexican–American War (1846-48) that revived Colt’s fortunes. Captain Samuel Walker, of the Texas Rangers and the US Army’s Regiment of Mounted Riflemen, was an admirer of Colt’s revolver having carried them in the field for a number of years. So much so that he wrote to Colt in 1846 saying:

“The pistols which you made… have been in use by the Rangers for three years, and I can say with confidence that it is the only good improvement I have seen. …Without your pistols we would not have had the confidence to have undertaken such daring adventures.”

Subsequently, the US government contracted Colt to produce 1,000 large calibre revolvers, the Model 1847. These huge, robust pistols had a fixed trigger and a loading lever as standard.

In 1847 Colt began manufacturing what has since become known as the ‘Colt Walker’, a large, .44 calibre revolver with a six-shot cylinder, that weighed 4lbs 9oz (2.07kg). He subcontracted the production to Eli Whitney Jr. who set up tooling to manufacture the new pistols. These were issued to the US Army’s mounted regiments including the Texas Mounted Volunteers, the US Mounted Riflemen and Dragoons. The success of the Colt Model 1847 Army Revolver paved the way for Colt’s future success.

Adapted Colt Paterson with Loading Lever

The Colt Paterson was an expensive item when it first appeared on the market, costing between $40 and $50 – well over $1,000 today. So then, as now, it makes sense that people who invested a considerable amount in a revolver would adapt and upgrade it if they could.

Below is another example of a Colt Paterson which was adapted. A No.5 Holster model, serial number 951, which had had its barrel cut down to 5 inches. This was done after it left the factory as the cut interrupts the original factory marker’s markings. The pistol also has a new cone front sight added.

The pistol we are examining in this blog/video, is part of the Cody Firearms Museum’s collection – serial number 954. It had a number of alterations to the revolver, principally the addition of a captive loading lever and a new rear sight. While the Patent Arms Company had begun adding a loading lever to their revolvers in 1839, these were of a different style and shape. Below we can see two original examples of Patent Arms Company factory loading levers.

Colt Paterson with long loading lever and scalloped cutout to allow capping, Serial number 818 (Collector Firearms)Colt Paterson with a short loading lever, serial number 515 (Rock Island Auctions)

It appears that loading levers of different designs were used on the post-1839 Patersons. The top revolver appears to use a lever similar to the one later utilised in the Model 1847. Both of the examples above differ significantly to that seen on serial number 954 (below), which is more akin to the loading levers seen on the Colt Model 1848 Percussion Army Revolver (or Colt Dragoon) and the later Model 1851 Navy. The profile of the levers and design and location of the pivot point differ. They both also lack any retention point near the end of the lever. This would suggest that #954’s lever is not a factory addition but something which was added later, copying the 1851 Navy’s retained lever which was patented in September 1850 (US #7,629). On close examination the cap cutout at the rear of the cylinder and the cut into the barrel assembly just in front of the cylinder to facilitate loading appear to differ from Patersons with factory loading levers.

As with other Colt percussion revolvers with loading levers, the rammer acts on the 6 o’clock cylinder. To load, the revolver was brought to half cock, powder was poured into the chamber, followed by round ball projectile. This was seated enough to allow it to line up with the rammer and the lever could then be pulled to ram the ball home. The cylinder could then be capped. The 1839 Paterson’s had a scalloped cutout to allow caps to be placed on the cylinder nipples without removing the cylinder.

Interestingly the revolver has a slightly bent rammer but seems to function fine despite this. This is perhaps an indication of hand-fitting by the gunsmith who adapted the revolver.

Close up of the Colt Paterson at half cock, note the slightly bent rammer (Photo: Matthew Moss, Courtesy of Cody Firearms Museum)

At some point, perhaps at the same time as the fitting of the lever, a new set of sights were fitted. With a more prominent front sight and a rear notch sight added to the top of the barrel, just in front of the cylinder. This was a feature that the 1851 Navy did not have, and no Colt revolver would have until decades later. The gunsmith appears to have cut the dove tail for the sight though the original decorative scroll engraving surrounding the maker’s mark.

Close up of the revolver’s markers markings and added rear sight, which cuts through some of the original decorative scroll work (Photo: Matthew Moss, Courtesy of Cody Firearms Museum)

More Photographs of the Adapted Colt Paterson:

Close up of the Colt Paterson’s brazed on loading lever retention catch (Photo: Matthew Moss, Courtesy of Cody Firearms Museum)

Close up of the serial number, 954, on the CFM’s Paterson No.5 (Photo: Matthew Moss, Courtesy of Cody Firearms Museum)

The revolvers produced at the Patent Arms Company’s Paterson factory in the late 1830s and early 1840s date from a fascinating period of American history, on the cusp of an era dominated by Samuel Colt’s revolvers. While the exact circumstances of the adaptations/upgrades made to the revolver we have examined at the Cody Firearms Museum are unclear it tells us that Colt’s revolvers, even early examples, were highly prized.

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During World War One the British Army had been early adopters of the light machine gun concept, recognising the mobility and firepower offered by the Lewis Gun as early as 1915. Despite the Lewis Gun’s proven track record after the war a lighter weapon was sought.

In the final months of World War One the US had begun fielding the Browning Automatic Rifle, Model of 1918, in what they had envisaged as a ‘walking fire’ role. Relatively soon after the war British Ordnance began the search for what they termed a ‘light gun’. They took an interest in the BAR ordering 25 Colt Model 1919 commercial guns for testing and evaluation at a cost of £1,575 in November 1920. According to James Ballou’s book on the BAR, Rock & a Hard Place, the serial numbers of these guns ran between C-100374 to C-100398. The Colt Model of 1919 differed little from the earlier US military model, the principle changes were the lack of a flash hider and the use of relocating of the recoil spring to the butt, acted on by a transfer rod, from inside the gas cylinder tube.

This batch of guns was adapted to chamber the rimmed British .303 round, necessitating a curved magazine, a .303 barrel, an adapted bolt, extractor and ejector. In April 1921 the BAR along with four other light machine guns (the Madsen, Beardmore-Farquhar, a Lewis Gun and strip and magazine fed Hotchkiss guns) at the School of Musketry at Hythe.

The Browning fared well in the testing with the evaluating officer stating that for a “light gas-operated weapon the Browning has done remarkably well…” In fact the Browning was selected as first preference out of the five weapons tested. The testing board felt it was suitably light and would be the cheapest to manufacture. The board made a series of suggestions to improve the BAR for British service:

Move the cocking handle to the right side of the weapon

Fit a light bipod which is height adjustable

Ejection port and magazine well dust covers

Gas regulator hole to be clear of threads of regulator

Improved method of fixing position of gas regulator

Stronger butt

Magazine well capable of receiving Lee-Enfield rifle magazines

No further action was taken until 1927 when it was decided that the Superintendent of Design should adapt several Brownings to improve the weapon for British service. According to Jame Ballou’s book these new modified BARs were not all from the original batch of test guns, at least one was a Colt gun purchased through FN.

The adapted BARs had carrying handles, flash hiders, bipods, Lewis Gun-style pistol grips, new rear sight and protected front post, an ejection port dust cover and a redesigned butt stock. A number of other changes were also made including switching the charging handle to the right (this change was found to be less necessary with the addition of a pistol grip).

While the modified BAR’s came fairly close to being adopted the principle problem remained the weapon’s limited 20 round magazine. Various larger magazines such as a 40-round box magazine from Colt and a 30-round drum were considered. By 1930 several new light machine guns had appeared and the Browning was beginning to look obsolescent. The Czech vz. 26 would eventually be adopted as the Bren.

We recently had the opportunity to examine what we believe to be a British trials BAR. Vic examined the gun finding that rather than a commercial Model of 1919, purchased for the first set of evaluations, it was marked as a Model of 1925. Interestingly, however, rather than resembling a Colt M1925 it had all the characteristics of an earlier M1919.

A still from Vic’s video showing the disassembled .303 Model 1925 (TAB)

The gun examined, serial number C-102723, falls outside of the serial range James Ballou states belonged to the 25 original .303 BARs. While it is marked M1925 the gun shares none of the characteristics of an M1925 – lacking the reshaped wooden foregrip, stubby pistol grip and rate of fire reducer. It does, however, have the 1919’s style of stock, foregrip and its relocated recoil spring. Additionally, the gun has had a folding carry handle, very similar to that of the later British trials BARs, added.

With little solid information available there could be a number of reasons for this. Perhaps the BAR Vic was able to examine was purchased for the later trials (between 1925-30) and it underwent minimal alterations – there is some variation between the documented surviving examples. The discrepancy between parts and the model name is curious. It is possibly a mix of parts were used to assemble the weapon during experimentation with configurations and an M1925 receiver was used as the basis of the gun but it was assembled with an M1919 barrel and furniture.

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Colt’s entry was perhaps the most conventional of the designs submitted. Based on the rifle the program sought to replace. Colt’s ACR was essentially an improved M16, which fired both conventional 5.56x45mm ammunition as well as a new 5.56mm duplex round. While the duplex round increase hit probability at shorter ranges, it impacted long range accuracy requiring the additional use of conventional M855 rounds.

Left and right side views of the Colt ACR (Matthew Moss)

It incorporated a variety of improvements including a new oil/spring hydraulic buffer to mitigate recoil. This resulted in a major decrease in the weapon’s recoil, Colt suggested as much as a 40% mitigation. A reshaped pistol grip and a hand guard which mounted a sighting rib for snap shooting – this stemmed from recommendations from the Human Engineering Lab. The weapon had a flat-top upper receiver which incorporated a weaver rail so a 3.5x optic (an early ECLAN) or a more conventional sight/carrying handle could be fitted.

(Matthew Moss)

The rifle’s collapsible six position telescopic butt stock was an improved version of that offered with Colt’s carbines. When at full extension the Colt ACR was the longest rifle tested, at 40.6 inch or 103 cm long. A distinctive proprietary muzzle brake compensator (MBC) designed by Knight’s Armament was also added. The Knight’s MBC reduced the rifle’s report by 13.5-decibels and also played an important role in recoil mitigation.

Close up of the Knight’s Armament designed muzzle device (Matthew Moss)Right-side close up of the rifle’s receiver and rail mounted Eclan sight (Matthew Moss)

Colt’s duplex rounds were developed by the Olin Corporation and placed two projectiles nose to tail. The projectiles were copper jacketed steel penetrators. In theory the lead projectile would strike at point of aim while the second would strike somewhere near point of aim with in a theoretically limited area of dispersion. The forward round was 35gr while the second was slightly lighter at 33gr.

Colt’s 5.56mm Duplex round (US Army)

During testing one of the duplex rounds was not properly seated inside the cartridge case and when fired became lodged in the barrel and during the course of fire and the weapon’s barrel blew when another round was fired. This was addressed by a slightly larger propellant charge.

Another negative to the Colt entry was that, in addition to having to carry two types of 5.56mm ammunition, its duplex round offered no improvement in weight and was infact slightly heavier than standard M855 ammunition. While the hydraulic buffer, muzzle device and furniture were not used later, some of the features developed for the ACR entry were later employed in the M16A3 and later A4. These included the selector configuration and the flat-top upper receiver.

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The four rifles tested during the final phases of the ACR program, AAI, Colt, H&K, Steyr (Matthew Moss)

With so few primary or secondary sources on the ACR program available, this article relies heavily on the 1990 program summary report written by the US Army Armament Research, Development and Engineering Center (ARDEC). Over the next three articles we will examine the AAI, Colt, and Steyr ACR entries. The H&K entry was covered earlier – here.

In the early 1980s the US Army began looking into what form a replacement for the M16A1 might take. The Joint Service Small Arms Program undertook a study and found that in the long term a “technology base should be developed to support a significant improvement in capability.” This meant the US infantryman’s next rifle would move away from conventional ammunition and actions.

The Advanced Combat Rifle program began in January 1985, to foster the development and select a rifle that would give troops a distinct advantage on the battlefield. The project’s ambitious aim was to address the human shortcomings of the average soldier in the field. It was found that combat stress, fear and fatigue negatively impacted on a rifleman’s ability to hit a target once engaged in combat.

The ACR program sought to compensate for this by maximising hit probability when engaging fleeting targets in battlefield conditions. The program called for:

“an enhancement in hit probability of at least 100 percent at combat ranges over the baseline performance of the M16A2 rifle… at extended ranges, the improvement required will be considerably greater than 100 percent. The weapon will be expected to enable the rifleman to detect rargets at ranges greater than 400m in offensive action and at least 1000m during the conduct of the defense.”

This was a tall order, calling for a weapon with an optic and the ability to engage long range targets, which were envisaged to be wearing body armour, but also engage fleeting targets. But the ACR program was far from the US military’ first ambitious small arms project.

The ACR program built on the Special Purpose Individual Weapon (SPIW) program that had been established in the 1950s to produce the next generation of infantry weapon capable of firing busts of flechettes at extremely high rates of fire to improve hit probability. This task proved technologically insurmountable during the 1950s and 60s. The SPIW program ended in the late 1960s, but was followed in the early 1970s by the Future Rifle Program which also proved a failure. Despite these failures the programs helped to push small arms technological boundaries.

In the video below, produced by ARDEC for the US Department of Defence, we see the ACR program briefly explained and the various rifles introduced with some firing footage:

The approaches used by the companies that entered the ACR competition varied greatly. Ranging from rifles with complex buffer systems to weapons that fired duplex and flechette rounds.

The first Request for Proposals was released in September 1985, with six companies successfully submitting proposals. These companies, which were awarded a Phase I contract, were: AAI Corporation, Ares Incorporated, Colt’s Manufacturing Company, Heckler & Koch (H&K), McDonnell Douglas Helicopter Systems (MDHS), and Steyr Mannlicher. In 1987, following Phase I of the program the entries from Ares and MDHS were dropped due to ‘hardware immaturity’ – the concepts were not developed enough. Both companies appealed and were allowed to enter designs to Phase II but neither was sufficiently developed to compete in the later trials and testing.

Each company approached the program’s aims in a different way. Two utilised flechette technology, which had been developed during the SPIW program, with the AAI using a brass cased round while the Steyr ACR used a polymer case. Colt’s entry used a duplex round with two projectiles stacked in the cartridge case. Heckler & Koch’s G11 used a complex buffer system to reduce felt recoil after firing a ‘hyper burst’ of three rounds at ~2,000 rounds per minute.

Lets take a look at the individual weapon systems:

AAI Corporation

AAI Corporation had long been involved in advanced firearms design, taking part in the US military’s previous programs. The AAI ACR was an evolution of the earlier SFR/XM19 rifle. AAI’s ACR was gas-operated, feeding from a 30 round box magazine and fired a brass cased flechette round in either single shot or a high cyclic rate three round bust.

It fired from a closed bolt and used a muzzle device to reduce muzzle climb during burst fire. AAI developed a polymer saboted steel 10.2 gr flechette which fitted within a standard M855 brass case. As a result the rifle uses a proprietary magazine to avoid the accidental chambering of conventional 5.56x45mm rounds. These rounds had a muzzle velocity of 4,600 ft/s.

The rifle was designed to mount a quick detachable 4x optic and had a white-highlighted shotgun-style rib sight along the barrel to aid in snap shooting. The rifle was one of the longest entries with an overall length of 40 inches or 101.6cm.

According to the ACR program summary the AAI entry proved to be a “mature design which performed in a reliable fashion” during the field trials.

Colt’s Manufacturing Company

Colt’s entry was perhaps the most conventional of the designs submitted. Based on the rifle the program sought to replace. Colt’s ACR was essentially an improved M16, which fired both conventional 5.56x45mm ammunition as well as a new 5.56mm duplex round. While the duplex round increase hit probability at shorter ranges, it impacted long range accuracy requiring the additional use of conventional M855 rounds.

It incorporated a variety of improvements including a new oil/spring hydraulic buffer to mitigate recoil. A reshaped pistol grip and a hand guard which mounted a sighting rib for snap shooting. The weapon had a flat-top upper receiver which was railed so a 3.5x optic (an early ECLAN) or a more conventional sight/carrying handle could be fitted.

Colt’s 5.56mm Duplex round (US Army)

The rifle’s collapsible six position telescopic butt stock was an improved version of that offered with Colt’s carbines. When at full extension the Colt ACR was the longest rifle tested, at 40.6 inch or 103 cm long. A distinctive proprietary muzzle brake compensator designed by Knight’s Armament was also added.

During testing one of the duplex rounds was not properly seated inside the cartridge case and when fired became lodged in the barrel and during the course of fire and the weapon’s barrel blew when another round was fired. This was addressed by a slightly larger propellant charge. Some of the features developed for the ACR entry were later employed in the M16A3 and later A4.

Heckler & Koch

Heckler & Koch had been involved in the West German Bundeswher’s attempts to create a next generation infantry weapon. The result was the G11, the G11 had been in development since the late 1960s and by the time it was entered into the ACR program it had evolved into a complex weapon unlike any other. Utilising a gas-operated, rotary breech to fire self-contained caseless 4.73×33mm projectiles. The rotary breech chamber was introduced as a means of clearing misfired, broken or defective cartridges from the enclosed system. Simplicity was sacrificed to achieve reliability.

The US had awarded H&K a contract to develop caseless ammunition, optics and the salvo concept in 1982. With the G11 in development they then entered the ACR program. The bullpup H&K was the shortest of the weapons entered into the trial at 29.5 inches / 74.9cm. It was equipped by a variable 1-3.5x optic designed by Swarovski.

The revolutionary ammunition was developed by Dynamit-Nobel AG.
The 4.73x33mm, 51gr round which was finalised comprised of a solid propellant material body which encased a primer, booster, projectile and a plastic nose cap. Dynamit-Nobel developed the High Ignition Temperature Propellant (HITP) in an effort to prevent accidental ignition (cook-off) of the ammunition’s outer propellant body. The ACR program summary notes that “the majority of the malfunctions/stoppages experience in the field experiment were ammunition related.”

The H&K ACR fed from a single stack, horizontally orientated 45-round magazine which sat above the barrel.

The G11 used a counter-recoil buffer mechanism to allow high rates of burst fire – hyper burst. When firing three round bursts the weapon could send the rounds downrange at a rate of ~2,000 rounds per minute, only when the last round has left the barrel does the barrel and action begin to recoil inside the stock along a central guide. The recoil impulse was then quite strong. When in sustained fire the rate of fire is closer to ~460 per minute. A more detailed explanation of the G11’s action can be found here.

Steyr-Mannlicher

Steyr-Mannlicher’s bullpup entry uses a gas piston driven rising chamber mechanism which rises and falls to chamber rounds as the action cycles. The Steyr ACR, like AAI’s entry, fires flechettes but Steyr’s are housed inside a cylindrical polymer case. The bullpup Steyr was the second shortest at 30 inches (76cm) and the lightest of the rifles submitted weighing 8.5 lbs (3.86kg).

The Steyr ACR borrows its ergonomics from its conventional forebearer, the AUG. With a moulded green plastic stock and a similar pistol grip, trigger and safety layout. Unlike the AUG, however, the ACR uses an AR-15 style charging handle located at the rear of the sight mounting block. The rifle could be fitted with a variable 1-3.5x optic.

The rifle does not use a conventional bolt, instead it has a rising chamber, as a result the rifle fired from an open bolt. A live round only entered the chamber after the trigger had been pulled, thus reducing the potential for cook-offs. Spent polymer cases were pushed out of the chamber and ejected from an opening just in front of the magazine well.

Steyr’s Polymer Cased Flechette round (US Army)

Feeding from a 24-round box magazine, made from the same translucent material used in conventional AUG magazines. The magazine goes from double stack to single stack, to allow it to feed reliably, as a result the capacity had to be shortened. A high capacity drum magazine was planned but not provided for the trials. The polymer case held a fin stabilised 9.85 gr flechette with a moulded four piece sabot which broke up soon after exiting the muzzle. This was identified as a shortcoming as it risked hitting nearby troops.

Specifications (From ACR Program Summary):

After several years of development, while the Army organised testing, the four firms delivered their prototypes in 1990. During Phase III the rifles were tested on the specially built Buckner Range – designed to recreate field conditions and create fleeting targets at various ranges. The M16A2 was used as a baseline weapon throughout all of the tests which included safety and engineering testing, lethality tests and testing in field conditions.

Initially planned as an all-services test both the US Navy and Marine Corps pulled out of the ACR program in 1987, leaving the Army and Air Force. With the testing complete it was found that none of the rifles proved to be significantly more lethal or effective than the M16A2 they were pitted against. The program summary put a rather positive spin on the program’s failings, concluding that despite the increased hit probabilities not being attained as a technology base program, the ACR program was a success. The soldiers taking part in the field tests performed better than expected and “the baseline performance of the M16A2 rifle was better than anticipated in terms of hit probability.”

The report concluded that the program had helped push small arms technology forward, noting that while flechettes proved to be too inaccurate for an individual weapon,

“The feasibility of caseless and lightweight plastic-cased ammunition has more than been demonstrated in this program. Few problems were experienced with the [H&K] caseless rifles in the test. The past technical barriers of cook-off and vulnerability have now been overcome. …plastic cases cannot be used in conventional weapons like the M16A2, but with weapons specifically designed for it, complete plastic cases are feasible.”

With the end of the ACR program the school of thought moved towards the use of high explosive and airburst munitions by individual soldiers. The Objective Individual Combat Weapon program ran throughout the early 1990s and while it lead to the adoption of some new weapons, such as the M320 grenade launcher, it also failed in its goal to create an integrated individual weapon system.

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